The app is designed to appeal to fans of Snapchat and other messaging apps that let people send self-destructing messages to friends.

Slingshot draws inevitable comparisons to Snapchat. Facebook even tried to buy Snapchat's maker — for $3 billion, according to published reports. But there are some key differences between the two.

— AVAILABILITY:

Facebook began making Slingshot available Tuesday to U.S. users, though the company accidentally released it last week in Apple's app store, giving some vigilant Facebook watchers an early glimpse before the app was removed from the store. Slingshot works with both Apple and Android devices. A Facebook account isn't required.

— HOW IT WORKS:

After downloading, you can sign up either with a Facebook account or your mobile phone number. You add contacts based on your Facebook friends and phone contacts.

Opening the app takes you to its camera, which has a "shoot" button for taking a snapshot and a "selfie" button for, you guessed it, a selfie. After taking a photo, you can type a message of up to 140 characters on it, or draw a picture. You can then send it to some or all of your Slingshot contacts.

— UNLIKE SNAPCHAT:

On Snapchat, people can see a photo sent to them by tapping on it and holding their finger down until it disappears, always within a few seconds. On Slingshot, you can see a message only if you send one back. Until you do, you'll only see a pixelated preview of what's in store. Facebook product designer Joey Flynn says this gives it a "reciprocal, kind of community feel."

Unlike with Snapchat, there is no time limit on when a message disappears. Once you are done looking at it, you can flick it off to the side and it self-destructs, much the same way you'd reject a potential mate on Tinder's dating app.

Slingshot also allows reaction shots. This splits your screen in half and lets you snap a photo to return to the sender. In this case, the recipient won't have to send back a message to view your response.

— SECOND TAKE:

Facebook had a previous Snapchat-like app called Poke, but it never caught on.

Slingshot is the second app to come out of Facebook's Creative Labs, an internal project designed to develop separate apps in a startup-like environment.

The first app from the lab was Paper, a social news reader that came out in February. The effort comes as Facebook seeks to broaden its reach beyond its 1.28 billion users by splintering off some of its functions to separate apps — and creating stand-alone apps for entirely new features and audiences.

Ten people have been working on Slingshot since January. It grew out of a December hackathon at Facebook where people were trying to figure out out "new ways of sharing," Flynn says.

Flynn says he thought of his two brothers, both of whom are "non-technical, they don't live in San Francisco." The three communicate on iMessage, the iPhone's built in-messaging system, and Flynn would often send photos and messages to his brothers to no response other than a "seen" receipt. Slingshot, he says, is intended to make sharing stuff more reciprocal.

— THE PROSPECTS:

Even Facebook acknowledges that its Creative Labs apps are starting small and might not reach an audience that Facebook itself reaches. The idea is to offer something for everyone.

But with a plethora of social sharing apps out there, Slingshot faces fiery competition — not just from Snapchat but also Instagram, which Facebook owns, and WhatsApp, which Facebook is buying for $19 billion. The challenge will be to show how it's different.

The app is designed to appeal to fans of Snapchat and other messaging apps that let people send self-destructing messages to friends.

Slingshot draws inevitable comparisons to Snapchat. Facebook even tried to buy Snapchat's maker — for $3 billion, according to published reports. But there are some key differences between the two.

— AVAILABILITY:

Facebook began making Slingshot available Tuesday to U.S. users, though the company accidentally released it last week in Apple's app store, giving some vigilant Facebook watchers an early glimpse before the app was removed from the store. Slingshot works with both Apple and Android devices. A Facebook account isn't required.

— HOW IT WORKS:

After downloading, you can sign up either with a Facebook account or your mobile phone number. You add contacts based on your Facebook friends and phone contacts.

Opening the app takes you to its camera, which has a "shoot" button for taking a snapshot and a "selfie" button for, you guessed it, a selfie. After taking a photo, you can type a message of up to 140 characters on it, or draw a picture. You can then send it to some or all of your Slingshot contacts.

— UNLIKE SNAPCHAT:

On Snapchat, people can see a photo sent to them by tapping on it and holding their finger down until it disappears, always within a few seconds. On Slingshot, you can see a message only if you send one back. Until you do, you'll only see a pixelated preview of what's in store. Facebook product designer Joey Flynn says this gives it a "reciprocal, kind of community feel."

Unlike with Snapchat, there is no time limit on when a message disappears. Once you are done looking at it, you can flick it off to the side and it self-destructs, much the same way you'd reject a potential mate on Tinder's dating app.

Slingshot also allows reaction shots. This splits your screen in half and lets you snap a photo to return to the sender. In this case, the recipient won't have to send back a message to view your response.

— SECOND TAKE:

Facebook had a previous Snapchat-like app called Poke, but it never caught on.

Slingshot is the second app to come out of Facebook's Creative Labs, an internal project designed to develop separate apps in a startup-like environment.

The first app from the lab was Paper, a social news reader that came out in February. The effort comes as Facebook seeks to broaden its reach beyond its 1.28 billion users by splintering off some of its functions to separate apps — and creating stand-alone apps for entirely new features and audiences.

Ten people have been working on Slingshot since January. It grew out of a December hackathon at Facebook where people were trying to figure out out "new ways of sharing," Flynn says.

Flynn says he thought of his two brothers, both of whom are "non-technical, they don't live in San Francisco." The three communicate on iMessage, the iPhone's built in-messaging system, and Flynn would often send photos and messages to his brothers to no response other than a "seen" receipt. Slingshot, he says, is intended to make sharing stuff more reciprocal.

— THE PROSPECTS:

Even Facebook acknowledges that its Creative Labs apps are starting small and might not reach an audience that Facebook itself reaches. The idea is to offer something for everyone.

But with a plethora of social sharing apps out there, Slingshot faces fiery competition — not just from Snapchat but also Instagram, which Facebook owns, and WhatsApp, which Facebook is buying for $19 billion. The challenge will be to show how it's different.